Many aircraft are equipped with one or more vision enhancing systems. Such vision enhancing systems are designed and configured to assist a pilot when flying in conditions that diminish the view from the cockpit. One example of a vision enhancing system is known as a synthetic vision system (hereinafter, “SVS”). A typical SVS is configured to work in conjunction with a position determining unit associated with the aircraft as well as dynamic sensors that sense aircraft altitude, heading, and orientation. The SVS includes or accesses a database containing information relating to the topography along the aircraft's flight path, such as information relating to the terrain and known man-made and natural obstacles proximate the aircraft flight path. The SVS receives inputs from the position determining unit indicative of the aircraft location and also receives inputs from the dynamic sensors. The SVS is configured to utilize the position, heading, altitude, and orientation information and the topographical information contained in the database, and generate a three-dimensional image that shows the topographical environment through which the aircraft is flying from the perspective of a person sitting in the cockpit of the aircraft. The three-dimensional image (also referred to herein as an “SVS image”) may be displayed to the pilot on any suitable display unit accessible to the pilot. The SVS image includes features that are graphically rendered including, without limitation, a synthetic perspective view of terrain and obstacles located proximate the aircraft's flight path. Using a SVS, the pilot can look at a display screen of the display unit to gain an understanding of the three-dimensional topographical environment through which the aircraft is flying and can also see what lies ahead. The pilot can also look at the display screen to determine aircraft proximity to one or more obstacles proximate the flight path.
The approach to landing and touch down on the runway of an aircraft is probably the most challenging task a pilot undertakes during normal operation. To perform the landing properly, the aircraft approaches the runway within an envelope of attitude, course, speed, and rate of descent limits. The course limits include, for example, both lateral limits and glide slope limits. In some instances visibility may be poor during approach and landing operations, resulting in what is known as instrument flight conditions. During instrument flight conditions, pilots rely on instruments, rather than visual references, to navigate the aircraft. Even during good weather conditions, pilots typically rely on instruments to some extent during the approach. Some SVS systems known in the art have been developed to supplement the pilot's reliance on instruments. For example, these systems allow pilots to descend to a low altitude, e.g., to 150 feet above the runway, using a combination of databases, advanced symbology, altimetry error detection, and high precision augmented coordinates. These systems utilize a wide area augmentation system (WAAS) GPS navigation aid, a flight management system, and an inertial navigation system to dynamically calibrate and determine a precise approach course to a runway and display the approach course relative to the runway centerline direction to pilots using the SVS.
The usefulness of these SVS systems for approach and landing is limited, however, by the accuracy of the topographical database, particularly in the terminal area of the airport. It has been discovered, for example, that in some instances, published terminal area topographical data may include unintended errors or biases in relation to the geographic position of certain features, such as runways, obstacles, etc. If these errors or biases are then introduced into the SVS topographical databases, then the 3-D rendered images presented to the pilot on the SVS may not match the aircraft's actual environment, which is problematic in the context of flying a precision approach to the airport supplemented by the SVS.
Accordingly, it is desirable to provide SVS systems and methods that are able to validate topographical information contained in a topographical database, in particular the geographical location of runways and obstacles in the terminal area of an airport. It is also desirable to provide such SVS systems and methods that are capable of correcting any errors or biases in the topographical database that may be determined by the validation. Furthermore, other desirable features and characteristics of exemplary embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.